CT Scans, Other Imaging Tests Becoming More Common

June 12, 2012 -- Another major study is pointing to significant increases in radiation exposure from the growing use of medical imaging tests such as CT scans.

For the latest study, which is published in the Journal of the American Medical Association, researchers combed through the medical records of millions of patients enrolled in six large HMOs around the U.S. They found that the percentages of patients who received high or very high doses of radiation from medical imaging tests roughly doubled over the last 15 years.

Researchers say the increases in radiation exposures seen in the new study were driven by a sharp uptick in the number of CT scans ordered for patients.

From 1996 to 2010, CT scan rates tripled at the HMOs, rising from 52 per 1,000 patients to 149 for every 1,000 patients.

The increase was especially surprising in a population of patients treated at HMOs. Similar increases in medical imaging tests have been documented among Medicare recipients and in the general population -- where doctors get paid for every scan they order. But HMOs use a different financial model. That means doctors are ordering more imaging tests even when there's no financial incentive to do so.

Experts say the new study shows the reasons for the rise may be more complex than had been previously realized and that greater education about the dangers of radiation may be needed to curb testing where it has become excessive.

"We should make ourselves aware as providers, make our patients aware, and make our referring physicians aware that there are risks to the population from radiation," says Bibb Allen, MD, vice chairman of the American College of Radiology. "We certainly think that the benefits of imaging outweigh the risks. But that doesn't mean we should ignore the risks," says Allen, who was not involved in the research.

Concerns Over CT Scans

A CT scan, which stands for computed tomography, combines X-ray imaging techniques with computer software to create multiple cross-sectional images of the body. CT images give a more detailed look at internal structures of the body. This can identify abnormalities and also help guide doctors with procedures. But CT scans also expose people to radiation doses that are 50 to 500 times higher than the dose delivered by a typical chest X-ray.